Kyle Busch Passed Out in Racing Simulator Before Hospitalization

NASCAR legend Kyle Busch tragically died at the age of 41 Thursday ... and we are starting to learn more about what happened prior to his shocking passing.

Before being hospitalized ... Busch was testing in a racing simulator in Concord on Wednesday when he became unresponsive -- and was rushed for medical care, the Associated Press reported via unnamed sources.

As TMZ reported ... Busch's family, racing team, Richard Childress Racing, and NASCAR announced the shocking news yesterday afternoon.

Earlier in the day, RCR revealed Kyle was in the hospital with a "severe illness," which came on the heels of his last Cup Series race on May 10 at Watkins Glen in upstate New York. During the race, Busch radioed his crew for medical aid. No other information has been provided by his team or family.

On TV, they noted that Kyle had been battling a sinus issue. However, he actually finished the race, coming in eighth place.

Kyle actually raced in a Truck Series race on May 15, winning the EcoSave 200. He then competed in the NASCAR All-Star Race on May 17, just four days before his death.